Anesthesia vaporizer



Nov. 24, 1964 P. SCHREIBER ANESTHESIA VAPORIZER Filed Sept. 28, 1962 INVENTOR Pezer Jch/"ez'ber' ATTORNEY-3 United States Patent 3,158,154 ANESTHESIA VAPORIZER Peter Schreiher, Luheeh, Germany, assignor to Otto Heinrich Driiger, Lubeelr, Germany Filed Sept. 28, 1962, Ser. No. 226,86 Claims priority, applieatien Germany, Nov. 18, 1951,

D 37,4?4 2 Claims. (Cl. 123-188) This invention relates to an anesthesia vaporizer and, in particular, to a vaporizer for an anesthesia apparatus which uses an anesthetic that is liquid at normal temperatures.

In an anesthesia apparatus using a vaporizer for the anesthetic that is liquid at normal temperatures, a portion of the gas is fed through the vaporizer while the other portion of the gas by-passes the vaporizer and then is combined with the gas that has gone through the vaporizer. In order to control the proportional ratio between the volume of gas flowing through the vaporizer and the volume of gas flowing through the by-pass, throttle valves are provided in the pipes. In one form of this apparatus, the by-pass pipe is provided with a constant flow throttle valve while a variable flow control valve is put in the pipe on the outlet side of the vaporizer. When this apparatus is used in combination with an apparatus for artificial respiration, the disadvantage exists in that pressure pulsations are formed in the vaporizer which cause pulsations in the gas being fed to the vaporizer as Well as in the gas flowing through the by-pass. These pulsations cause, among otherthings, a backflow of the vaporized anesthetics from the vaporizer so that the vaporized anesthetics reach the oy-pass line by way of the feed pipe to the vaporizer. Consequently, the adjusted mixture of the gases is uncontrollably changed by this backflow of the anesthetic gas from the vaporizer.

The object of this invention is to avoid the above-mentioned disadvantage in a vaporizer for anesthetics liquid at normal temperatures. According to this invention, the gas feed or intake pipe for the vaporizer includes a length of pipe such that the back pressure flow due to pulsations in the vaporizer will not reach the by-pass line. Consequently, the advantage is achieved in that pressure pulsations in the vaporizer will not cause any change in the mixture ratio between the gases from the vaporizer and the gases from the by-pass line as discharged from the device.

The means by which the objects of the invention are obtained are described more fully with reference to the accompanying schematic drawing of a cross-section through the device.

Gas, such as air, an air mixture, a nutritive gas mixture with or without the addition of cyclopropane, laughing gas or the like, enters the device through pipe 1 leading into distribution chamber 2. A pipe 3 connects chamber 2 with the vaporizer 4 containing an anesthetic liquid at normal temperatures. Outlet pipe 5 containing a variable control throttle valve 6 connects with pipe 7 extending into the gas mixing chamber 8.

The by-pass line 9 is joined in parallel to vaporizer 4 and contains a throttle valve 16. Both valves 6 and 19 are adjustable.

6 Outlet tube 11 from the chamber 8 is 3,158,154 Patented Nov. 24, 1964 connectable to pipe means leading to the patient.

A relatively long piece of pipe 12, preferably in the form of a pipe coil, is included in the pipe 3 and has a length sufiicient to satisfy the following conditions. When the device is in use, pressure pulsations occur in the vaporizer chamber 13 in accordance with the pulsations produced in the pipe 11 and mixing chamber 8 by reason of the breathing of the patient. These pressure pulsations in vaporizer chamber 13 cause a blackflow of gas through pipe 3 into distribution chamber 2 and into by-pass line 9. In the prior art apparatus, this leads to the fact that, when the patient inhales, anesthetic gas in an uncontrollable volume is fed through distribution chamber 2 and by-pass line 9. This means that an undesired amount of vaporized narcotic is given the patient. According to this invention, the length of the included pipe 12 in the intake pipe 3 is such that, when a maximum pressure pulse occurs in vaporizing chamber 13, the gas enriched with the vaporized anesthetic will not backdow all the Way to the distribution chamber 2 and, consequently, will not reach the mixing chamber 8 through by-pass line 9.

Having now described the means by which the objects of the invention are obtained, I claim:

1. In a vaporizer for an anesthetic, liquid at normal temperatures, as used in an anesthesia apparatus, said vaporizer having a gas inlet distributor chamber, pipe means for supplying gas into said distributor chamber, a liquid anesthetic vaporizer unit, first pipe means joining said distributor chamber to said vaporizer unit for leading intake gas from said distributor chamber into said unit, a gas mixing chamber, second pipe means connecting said vaporizer unit to said mixing chamber for leading vaporized gas from said unit to said mixing chamber, by-pass pipe means joining said distributor chamber to said .illiX- ing chamber, valve means for controlling the flow of gas through said vaporizer, and outlet tube means for exhaust ing gas from said mixing chamber, the improvement in which said first pipe means has a relatively long length as compared to said second pipe means to prevent normal gas backfiow from said vaporizer unit due to pressure pulsations caused by the breathing of the user of the vaporizer from reaching said distribution chamber and said by-pass pipe means.

2. In a vaporizer as in claim 1, said first pipe means comprising a tube coil.

References Cited by the Examiner UNITED STATES PATENTS 1,302,133 4/19 Clark l28203 2,042,474 6/36 McKesson 128-203 2,136,245 11/38 Heidbrink l28203 3,018,777 1/62 Dietrich 128-210 FOREIGN PATENTS 181,355 3/55 Austria.

RICHARD A. GAUDET, Primary Examiner. JORDAN FRANKLIN, Examiner. 

1. IN A VAPORIZER FOR AN ANESTHETIC, LIQUID AT NORMAL TEMPERATURES, AS USED IN AN ANESTHESIA APPARATUS, SAID VAPORIZER HAVING A GAS INLET DISTRIBUTOR CHAMBER, PIPE MEANS FOR SUPPLYING GAS INTO SAID DISTRIBUTOR CHAMBER, A LIQUID ANESTHETIC VAPORIZER UNIT, FIRST PIPE MEANS JOINING SAID DISTRIBUTOR CHAMBER TO SAID VAPORIZER UNIT FOR LEADING INTAKE GAS FROM SAID DISTRIBUTOR CHAMBER INTO SAID UNIT, A GAS MIXING CHAMBER, SECOND PIPE MEANS CONNECTING SAID VAPORIZER UNIT TO SAID MIXING CHAMBER FOR LEADING VAPORIZED GAS FROM SAID UNIT TO SAID MIXING CHAMBER, BY-PASS PIPE MEANS JOINING SAID DISTRIBUTOR CHAMBER TO SAID MIXING CHAMBER, VALVE MEANS FOR CONTROLLING THE FLOW OF GAS THROUGH SAID VAPORIZER, AND OUTLET TUBE MEANS FOR EXHAUSTING GAS FROM SAID MIXING CHAMBER, THE IMPROVEMENT IN WHICH SAID FIRST PIPE MEANS HAS A RELATIVELY LONG LENGTH AS COMPARED TO SAID SECOND PIPE MEANS TO PREVENT NORMAL GAS BACKFLOW FROM SAID VAPORIZER UNIT DUE TO PRESSURE PULSATIONS CAUSED BY THE BREATHING OF THE USER OF THE VAPORIZER FROM REACHING SAID DISTRIBUTION CHAMBER AND SAID BY-PASS PIPE MEANS. 